Some beginner questions...

mike earussi wrote:

The SD15 blows out highlights very easily, so you should treat it like shooting slide film, i.e. expose for the highlights and let the shadows fall where they may and then try to recover some of them in SPP.

Also never fully trust in-camera metering, just use it as a guide and then adjust as necessary.

Always shoot in raw as jpeg has less DR.

ISO matters, 100 has the best DR and 50 has the less noise. At 200 and above DR starts to decrease.

In SPP all of the camera modes (neutral, standard, etc.) alter the actual raw data. If you want to see what the raw file actually looks like then set it to X3F which is very flat and lifeless, but at least you then have access to the entire file.

I normally shoot at iso 50 or 100 in aperture priority to get the camera's estimated exposure, then switch to manual to fine tune it and process in SPP in Neutral mode and then adjust as needed. But the SD15 was the last Sigma camera that can also be processed in ACR. So if you're not getting the results you like in SPP, try ACR instead.

This is the kind of reply I would have written, too. Always shoot in RAW, shoot like you were shooting a slide film (expose for the highlights), and shoot in ISO 100 whenever possible. It's a bit trickier than with many other dSLR's but it's worth the effort, and the experience is the closest one can get to shooting an Ektachrome 100 slide film with a digital SLR. I used to shoot in standard mode mostly, and then tweaked the files in post if/when necessary.

As for processing the SD15 RAW files, there's yet another option, namely Iridient Developer. http://www.iridientdigital.com/products/rawdeveloper.html

The results it delivers are pretty nice, sometimes perhaps a bit "sweeter" than those from SPP, but which one is better is a matter of taste, and each result can be tweaked to your liking. The same app can also handle a lot of other RAW formats, too.